This invention relates to a franking machine system for updating the credit available in a franking machine for franking mail items and in particular to a system for updating the credit available in a plurality of franking machines. The invention also relates to a controller for use in such a system.
Commonly, franking machines for franking mail items are provided with means to store a value of credit available for use in franking items and as franking takes place the credit value is decremented to correspond to the remaining credit available for use. When the credit has been decremented to a predetermined minimum value the franking machine is rendered inoperative to carry further franking of items. For reasons of security and to prevent fraudulent use of the franking machine, the part of the machine for carrying out accounting functions and for storing data relating to the use of the machine, including the value of credit available, is contained within a sealed secure housing. Access to this part of the machine by the user is not authorized and updating of the credit value available can only be carried out by the postal authority. Previously it has been necessary for the user to take the machine, or at least that part of the machine which carries out accounting functions and stores the credit value, to the postal authority and upon payment by the user the postal authority accesses the machine to enter a new value of credit and then reseals the machine. In order to overcome the inconvenience of needing to physically transport a part of the franking machine to the postal authority it has been proposed to accomplish the operation of updating of credit on the users premises by transmission of coded data by telephone. In such proposals, generally the franking machine is constructed to generate a sequence of codes, one being used at each credit updating. The postal authority provides to the user, via the telephone, data in encrypted form which includes the current code held in the franking machine. After decryption of the data, the machine compares the internal and entered codes and if they agree the credit value is updated.
Known methods of updating credit in franking machines have been based upon the postal authority having access either directly or via a telephone line with each individual franking machine licensed by the postal authority. While this is satisfactory for users with only a single franking machine, for users who have a number of franking machines the present methods are inconvenient and involve the user and the postal authorities in a large volume of financial accounting.